mpv/sub/dec_sub.c

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/*
* This file is part of mpv.
*
Relicense some non-MPlayer source files to LGPL 2.1 or later This covers source files which were added in mplayer2 and mpv times only, and where all code is covered by LGPL relicensing agreements. There are probably more files to which this applies, but I'm being conservative here. A file named ao_sdl.c exists in MPlayer too, but the mpv one is a complete rewrite, and was added some time after the original ao_sdl.c was removed. The same applies to vo_sdl.c, for which the SDL2 API is radically different in addition (MPlayer supports SDL 1.2 only). common.c contains only code written by me. But common.h is a strange case: although it originally was named mp_common.h and exists in MPlayer too, by now it contains only definitions written by uau and me. The exceptions are the CONTROL_ defines - thus not changing the license of common.h yet. codec_tags.c contained once large tables generated from MPlayer's codecs.conf, but all of these tables were removed. From demux_playlist.c I'm removing a code fragment from someone who was not asked; this probably could be done later (see commit 15dccc37). misc.c is a bit complicated to reason about (it was split off mplayer.c and thus contains random functions out of this file), but actually all functions have been added post-MPlayer. Except get_relative_time(), which was written by uau, but looks similar to 3 different versions of something similar in each of the Unix/win32/OSX timer source files. I'm not sure what that means in regards to copyright, so I've just moved it into another still-GPL source file for now. screenshot.c once had some minor parts of MPlayer's vf_screenshot.c, but they're all gone.
2016-01-19 17:36:06 +00:00
* mpv is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* mpv is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
Relicense some non-MPlayer source files to LGPL 2.1 or later This covers source files which were added in mplayer2 and mpv times only, and where all code is covered by LGPL relicensing agreements. There are probably more files to which this applies, but I'm being conservative here. A file named ao_sdl.c exists in MPlayer too, but the mpv one is a complete rewrite, and was added some time after the original ao_sdl.c was removed. The same applies to vo_sdl.c, for which the SDL2 API is radically different in addition (MPlayer supports SDL 1.2 only). common.c contains only code written by me. But common.h is a strange case: although it originally was named mp_common.h and exists in MPlayer too, by now it contains only definitions written by uau and me. The exceptions are the CONTROL_ defines - thus not changing the license of common.h yet. codec_tags.c contained once large tables generated from MPlayer's codecs.conf, but all of these tables were removed. From demux_playlist.c I'm removing a code fragment from someone who was not asked; this probably could be done later (see commit 15dccc37). misc.c is a bit complicated to reason about (it was split off mplayer.c and thus contains random functions out of this file), but actually all functions have been added post-MPlayer. Except get_relative_time(), which was written by uau, but looks similar to 3 different versions of something similar in each of the Unix/win32/OSX timer source files. I'm not sure what that means in regards to copyright, so I've just moved it into another still-GPL source file for now. screenshot.c once had some minor parts of MPlayer's vf_screenshot.c, but they're all gone.
2016-01-19 17:36:06 +00:00
* GNU Lesser General Public License for more details.
*
Relicense some non-MPlayer source files to LGPL 2.1 or later This covers source files which were added in mplayer2 and mpv times only, and where all code is covered by LGPL relicensing agreements. There are probably more files to which this applies, but I'm being conservative here. A file named ao_sdl.c exists in MPlayer too, but the mpv one is a complete rewrite, and was added some time after the original ao_sdl.c was removed. The same applies to vo_sdl.c, for which the SDL2 API is radically different in addition (MPlayer supports SDL 1.2 only). common.c contains only code written by me. But common.h is a strange case: although it originally was named mp_common.h and exists in MPlayer too, by now it contains only definitions written by uau and me. The exceptions are the CONTROL_ defines - thus not changing the license of common.h yet. codec_tags.c contained once large tables generated from MPlayer's codecs.conf, but all of these tables were removed. From demux_playlist.c I'm removing a code fragment from someone who was not asked; this probably could be done later (see commit 15dccc37). misc.c is a bit complicated to reason about (it was split off mplayer.c and thus contains random functions out of this file), but actually all functions have been added post-MPlayer. Except get_relative_time(), which was written by uau, but looks similar to 3 different versions of something similar in each of the Unix/win32/OSX timer source files. I'm not sure what that means in regards to copyright, so I've just moved it into another still-GPL source file for now. screenshot.c once had some minor parts of MPlayer's vf_screenshot.c, but they're all gone.
2016-01-19 17:36:06 +00:00
* You should have received a copy of the GNU Lesser General Public
* License along with mpv. If not, see <http://www.gnu.org/licenses/>.
*/
#include <stdlib.h>
#include <stdbool.h>
#include <string.h>
#include <math.h>
#include <assert.h>
#include <pthread.h>
#include "config.h"
#include "demux/demux.h"
#include "sd.h"
#include "dec_sub.h"
#include "options/m_config.h"
#include "options/options.h"
2013-12-21 18:06:37 +00:00
#include "common/global.h"
#include "common/msg.h"
#include "common/recorder.h"
#include "misc/dispatch.h"
#include "osdep/threads.h"
extern const struct sd_functions sd_ass;
extern const struct sd_functions sd_lavc;
static const struct sd_functions *const sd_list[] = {
&sd_lavc,
&sd_ass,
NULL
};
struct dec_sub {
pthread_mutex_t lock;
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struct mp_log *log;
struct mpv_global *global;
struct mp_subtitle_opts *opts;
struct m_config_cache *opts_cache;
struct mp_recorder_sink *recorder_sink;
struct attachment_list *attachments;
struct sh_stream *sh;
Implement backwards playback See manpage additions. This is a huge hack. You can bet there are shit tons of bugs. It's literally forcing square pegs into round holes. Hopefully, the manpage wall of text makes it clear enough that the whole shit can easily crash and burn. (Although it shouldn't literally crash. That would be a bug. It possibly _could_ start a fire by entering some sort of endless loop, not a literal one, just something where it tries to do work without making progress.) (Some obvious bugs I simply ignored for this initial version, but there's a number of potential bugs I can't even imagine. Normal playback should remain completely unaffected, though.) How this works is also described in the manpage. Basically, we demux in reverse, then we decode in reverse, then we render in reverse. The decoding part is the simplest: just reorder the decoder output. This weirdly integrates with the timeline/ordered chapter code, which also has special requirements on feeding the packets to the decoder in a non-straightforward way (it doesn't conflict, although a bugmessmass breaks correct slicing of segments, so EDL/ordered chapter playback is broken in backward direction). Backward demuxing is pretty involved. In theory, it could be much easier: simply iterating the usual demuxer output backward. But this just doesn't fit into our code, so there's a cthulhu nightmare of shit. To be specific, each stream (audio, video) is reversed separately. At least this means we can do backward playback within cached content (for example, you could play backwards in a live stream; on that note, it disables prefetching, which would lead to losing new live video, but this could be avoided). The fuckmess also meant that I didn't bother trying to support subtitles. Subtitles are a problem because they're "sparse" streams. They need to be "passively" demuxed: you don't try to read a subtitle packet, you demux audio and video, and then look whether there was a subtitle packet. This means to get subtitles for a time range, you need to know that you demuxed video and audio over this range, which becomes pretty messy when you demux audio and video backwards separately. Backward display is the most weird (and potentially buggy) part. To avoid that we need to touch a LOT of timing code, we negate all timestamps. The basic idea is that due to the navigation, all comparisons and subtractions of timestamps keep working, and you don't need to touch every single of them to "reverse" them. E.g.: bool before = pts_a < pts_b; would need to be: bool before = forward ? pts_a < pts_b : pts_a > pts_b; or: bool before = pts_a * dir < pts_b * dir; or if you, as it's implemented now, just do this after decoding: pts_a *= dir; pts_b *= dir; and then in the normal timing/renderer code: bool before = pts_a < pts_b; Consequently, we don't need many changes in the latter code. But some assumptions inhererently true for forward playback may have been broken anyway. What is mainly needed is fixing places where values are passed between positive and negative "domains". For example, seeking and timestamp user display always uses positive timestamps. The main mess is that it's not obvious which domain a given variable should or does use. Well, in my tests with a single file, it suddenly started to work when I did this. I'm honestly surprised that it did, and that I didn't have to change a single line in the timing code past decoder (just something minor to make external/cached text subtitles display). I committed it immediately while avoiding thinking about it. But there really likely are subtle problems of all sorts. As far as I'm aware, gstreamer also supports backward playback. When I looked at this years ago, I couldn't find a way to actually try this, and I didn't revisit it now. Back then I also read talk slides from the person who implemented it, and I'm not sure if and which ideas I might have taken from it. It's possible that the timestamp reversal is inspired by it, but I didn't check. (I think it claimed that it could avoid large changes by changing a sign?) VapourSynth has some sort of reverse function, which provides a backward view on a video. The function itself is trivial to implement, as VapourSynth aims to provide random access to video by frame numbers (so you just request decreasing frame numbers). From what I remember, it wasn't exactly fluid, but it worked. It's implemented by creating an index, and seeking to the target on demand, and a bunch of caching. mpv could use it, but it would either require using VapourSynth as demuxer and decoder for everything, or replacing the current file every time something is supposed to be played backwards. FFmpeg's libavfilter has reversal filters for audio and video. These require buffering the entire media data of the file, and don't really fit into mpv's architecture. It could be used by playing a libavfilter graph that also demuxes, but that's like VapourSynth but worse.
2019-05-18 00:10:51 +00:00
int play_dir;
sub: align ytdl-hook secondary subs to the top 29e15e6248 prefixed youtube-dl's subs url with an edl prefix to not download them until they're selected, which is useful when there are many sub languages. But this prefix broke the alignment of secondary subs, which would overlap the primary subs instead of always being placed at the top. This can be tested with --sub-file='edl://!no_clip;!delay_open,media_type=sub;secondary_sub.srt' When a sub is added, sub.c:reinit_sub() is called. This calls in init_subdec() -> dec_sub.c:sub_create() -> init_decoder() -> sd_ass:init(). Then reinit_sub() calls sub_control(track->d_sub, SD_CTRL_SET_TOP, &(bool){!!order}) which sets sd_ass_priv.on_top = true for secondary subs. But for EDL subs the real sub is initialized again when in dec_sub.c:sub_read_packets() is_new_segment() returns true and update_segment() is called, or when sub_get_bitmaps() calls update_segment(). update_segment() then calls init_decoder(), which calls sd_ass:init(), so sd_ass_priv is reinitialized, and its on_top property is left false. This commit sets it to true again. For URLs that need to be downloaded it seems that the update_segment() call that reinitializes sd_ass_priv is always the one in sub_read_packets(), but with local subs sub_get_bitmaps() is usually called earlier (though there shouldn't be a reason to use the EDL URL for local subs), so I added the order parameter to sub_create(), rather than adding it to all of update_segment(), sub_read_packets() and sub_get_bitmaps(). Also removes the cast to bool in the other sub_control call, since sub/sd_ass.c:control already casts arg to bool when cmd is SD_CTRL_SET_TOP.
2021-08-10 20:11:53 +00:00
int order;
double last_pkt_pts;
bool preload_attempted;
double video_fps;
double sub_speed;
Rewrite ordered chapters and timeline stuff This uses a different method to piece segments together. The old approach basically changes to a new file (with a new start offset) any time a segment ends. This meant waiting for audio/video end on segment end, and then changing to the new segment all at once. It had a very weird impact on the playback core, and some things (like truly gapless segment transitions, or frame backstepping) just didn't work. The new approach adds the demux_timeline pseudo-demuxer, which presents an uniform packet stream from the many segments. This is pretty similar to how ordered chapters are implemented everywhere else. It also reminds of the FFmpeg concat pseudo-demuxer. The "pure" version of this approach doesn't work though. Segments can actually have different codec configurations (different extradata), and subtitles are most likely broken too. (Subtitles have multiple corner cases which break the pure stream-concatenation approach completely.) To counter this, we do two things: - Reinit the decoder with each segment. We go as far as allowing concatenating files with completely different codecs for the sake of EDL (which also uses the timeline infrastructure). A "lighter" approach would try to make use of decoder mechanism to update e.g. the extradata, but that seems fragile. - Clip decoded data to segment boundaries. This is equivalent to normal playback core mechanisms like hr-seek, but now the playback core doesn't need to care about these things. These two mechanisms are equivalent to what happened in the old implementation, except they don't happen in the playback core anymore. In other words, the playback core is completely relieved from timeline implementation details. (Which honestly is exactly what I'm trying to do here. I don't think ordered chapter behavior deserves improvement, even if it's bad - but I want to get it out from the playback core.) There is code duplication between audio and video decoder common code. This is awful and could be shareable - but this will happen later. Note that the audio path has some code to clip audio frames for the purpose of codec preroll/gapless handling, but it's not shared as sharing it would cause more pain than it would help.
2016-02-15 20:04:07 +00:00
struct mp_codec_params *codec;
double start, end;
double last_vo_pts;
struct sd *sd;
Rewrite ordered chapters and timeline stuff This uses a different method to piece segments together. The old approach basically changes to a new file (with a new start offset) any time a segment ends. This meant waiting for audio/video end on segment end, and then changing to the new segment all at once. It had a very weird impact on the playback core, and some things (like truly gapless segment transitions, or frame backstepping) just didn't work. The new approach adds the demux_timeline pseudo-demuxer, which presents an uniform packet stream from the many segments. This is pretty similar to how ordered chapters are implemented everywhere else. It also reminds of the FFmpeg concat pseudo-demuxer. The "pure" version of this approach doesn't work though. Segments can actually have different codec configurations (different extradata), and subtitles are most likely broken too. (Subtitles have multiple corner cases which break the pure stream-concatenation approach completely.) To counter this, we do two things: - Reinit the decoder with each segment. We go as far as allowing concatenating files with completely different codecs for the sake of EDL (which also uses the timeline infrastructure). A "lighter" approach would try to make use of decoder mechanism to update e.g. the extradata, but that seems fragile. - Clip decoded data to segment boundaries. This is equivalent to normal playback core mechanisms like hr-seek, but now the playback core doesn't need to care about these things. These two mechanisms are equivalent to what happened in the old implementation, except they don't happen in the playback core anymore. In other words, the playback core is completely relieved from timeline implementation details. (Which honestly is exactly what I'm trying to do here. I don't think ordered chapter behavior deserves improvement, even if it's bad - but I want to get it out from the playback core.) There is code duplication between audio and video decoder common code. This is awful and could be shareable - but this will happen later. Note that the audio path has some code to clip audio frames for the purpose of codec preroll/gapless handling, but it's not shared as sharing it would cause more pain than it would help.
2016-02-15 20:04:07 +00:00
struct demux_packet *new_segment;
};
static void update_subtitle_speed(struct dec_sub *sub)
{
struct mp_subtitle_opts *opts = sub->opts;
sub->sub_speed = 1.0;
if (sub->video_fps > 0 && sub->codec->frame_based > 0) {
MP_VERBOSE(sub, "Frame based format, dummy FPS: %f, video FPS: %f\n",
sub->codec->frame_based, sub->video_fps);
sub->sub_speed *= sub->codec->frame_based / sub->video_fps;
}
if (opts->sub_fps && sub->video_fps)
sub->sub_speed *= opts->sub_fps / sub->video_fps;
sub->sub_speed *= opts->sub_speed;
}
// Return the subtitle PTS used for a given video PTS.
static double pts_to_subtitle(struct dec_sub *sub, double pts)
{
struct mp_subtitle_opts *opts = sub->opts;
if (pts != MP_NOPTS_VALUE)
Implement backwards playback See manpage additions. This is a huge hack. You can bet there are shit tons of bugs. It's literally forcing square pegs into round holes. Hopefully, the manpage wall of text makes it clear enough that the whole shit can easily crash and burn. (Although it shouldn't literally crash. That would be a bug. It possibly _could_ start a fire by entering some sort of endless loop, not a literal one, just something where it tries to do work without making progress.) (Some obvious bugs I simply ignored for this initial version, but there's a number of potential bugs I can't even imagine. Normal playback should remain completely unaffected, though.) How this works is also described in the manpage. Basically, we demux in reverse, then we decode in reverse, then we render in reverse. The decoding part is the simplest: just reorder the decoder output. This weirdly integrates with the timeline/ordered chapter code, which also has special requirements on feeding the packets to the decoder in a non-straightforward way (it doesn't conflict, although a bugmessmass breaks correct slicing of segments, so EDL/ordered chapter playback is broken in backward direction). Backward demuxing is pretty involved. In theory, it could be much easier: simply iterating the usual demuxer output backward. But this just doesn't fit into our code, so there's a cthulhu nightmare of shit. To be specific, each stream (audio, video) is reversed separately. At least this means we can do backward playback within cached content (for example, you could play backwards in a live stream; on that note, it disables prefetching, which would lead to losing new live video, but this could be avoided). The fuckmess also meant that I didn't bother trying to support subtitles. Subtitles are a problem because they're "sparse" streams. They need to be "passively" demuxed: you don't try to read a subtitle packet, you demux audio and video, and then look whether there was a subtitle packet. This means to get subtitles for a time range, you need to know that you demuxed video and audio over this range, which becomes pretty messy when you demux audio and video backwards separately. Backward display is the most weird (and potentially buggy) part. To avoid that we need to touch a LOT of timing code, we negate all timestamps. The basic idea is that due to the navigation, all comparisons and subtractions of timestamps keep working, and you don't need to touch every single of them to "reverse" them. E.g.: bool before = pts_a < pts_b; would need to be: bool before = forward ? pts_a < pts_b : pts_a > pts_b; or: bool before = pts_a * dir < pts_b * dir; or if you, as it's implemented now, just do this after decoding: pts_a *= dir; pts_b *= dir; and then in the normal timing/renderer code: bool before = pts_a < pts_b; Consequently, we don't need many changes in the latter code. But some assumptions inhererently true for forward playback may have been broken anyway. What is mainly needed is fixing places where values are passed between positive and negative "domains". For example, seeking and timestamp user display always uses positive timestamps. The main mess is that it's not obvious which domain a given variable should or does use. Well, in my tests with a single file, it suddenly started to work when I did this. I'm honestly surprised that it did, and that I didn't have to change a single line in the timing code past decoder (just something minor to make external/cached text subtitles display). I committed it immediately while avoiding thinking about it. But there really likely are subtle problems of all sorts. As far as I'm aware, gstreamer also supports backward playback. When I looked at this years ago, I couldn't find a way to actually try this, and I didn't revisit it now. Back then I also read talk slides from the person who implemented it, and I'm not sure if and which ideas I might have taken from it. It's possible that the timestamp reversal is inspired by it, but I didn't check. (I think it claimed that it could avoid large changes by changing a sign?) VapourSynth has some sort of reverse function, which provides a backward view on a video. The function itself is trivial to implement, as VapourSynth aims to provide random access to video by frame numbers (so you just request decreasing frame numbers). From what I remember, it wasn't exactly fluid, but it worked. It's implemented by creating an index, and seeking to the target on demand, and a bunch of caching. mpv could use it, but it would either require using VapourSynth as demuxer and decoder for everything, or replacing the current file every time something is supposed to be played backwards. FFmpeg's libavfilter has reversal filters for audio and video. These require buffering the entire media data of the file, and don't really fit into mpv's architecture. It could be used by playing a libavfilter graph that also demuxes, but that's like VapourSynth but worse.
2019-05-18 00:10:51 +00:00
pts = (pts * sub->play_dir - opts->sub_delay) / sub->sub_speed;
return pts;
}
static double pts_from_subtitle(struct dec_sub *sub, double pts)
{
struct mp_subtitle_opts *opts = sub->opts;
if (pts != MP_NOPTS_VALUE)
Implement backwards playback See manpage additions. This is a huge hack. You can bet there are shit tons of bugs. It's literally forcing square pegs into round holes. Hopefully, the manpage wall of text makes it clear enough that the whole shit can easily crash and burn. (Although it shouldn't literally crash. That would be a bug. It possibly _could_ start a fire by entering some sort of endless loop, not a literal one, just something where it tries to do work without making progress.) (Some obvious bugs I simply ignored for this initial version, but there's a number of potential bugs I can't even imagine. Normal playback should remain completely unaffected, though.) How this works is also described in the manpage. Basically, we demux in reverse, then we decode in reverse, then we render in reverse. The decoding part is the simplest: just reorder the decoder output. This weirdly integrates with the timeline/ordered chapter code, which also has special requirements on feeding the packets to the decoder in a non-straightforward way (it doesn't conflict, although a bugmessmass breaks correct slicing of segments, so EDL/ordered chapter playback is broken in backward direction). Backward demuxing is pretty involved. In theory, it could be much easier: simply iterating the usual demuxer output backward. But this just doesn't fit into our code, so there's a cthulhu nightmare of shit. To be specific, each stream (audio, video) is reversed separately. At least this means we can do backward playback within cached content (for example, you could play backwards in a live stream; on that note, it disables prefetching, which would lead to losing new live video, but this could be avoided). The fuckmess also meant that I didn't bother trying to support subtitles. Subtitles are a problem because they're "sparse" streams. They need to be "passively" demuxed: you don't try to read a subtitle packet, you demux audio and video, and then look whether there was a subtitle packet. This means to get subtitles for a time range, you need to know that you demuxed video and audio over this range, which becomes pretty messy when you demux audio and video backwards separately. Backward display is the most weird (and potentially buggy) part. To avoid that we need to touch a LOT of timing code, we negate all timestamps. The basic idea is that due to the navigation, all comparisons and subtractions of timestamps keep working, and you don't need to touch every single of them to "reverse" them. E.g.: bool before = pts_a < pts_b; would need to be: bool before = forward ? pts_a < pts_b : pts_a > pts_b; or: bool before = pts_a * dir < pts_b * dir; or if you, as it's implemented now, just do this after decoding: pts_a *= dir; pts_b *= dir; and then in the normal timing/renderer code: bool before = pts_a < pts_b; Consequently, we don't need many changes in the latter code. But some assumptions inhererently true for forward playback may have been broken anyway. What is mainly needed is fixing places where values are passed between positive and negative "domains". For example, seeking and timestamp user display always uses positive timestamps. The main mess is that it's not obvious which domain a given variable should or does use. Well, in my tests with a single file, it suddenly started to work when I did this. I'm honestly surprised that it did, and that I didn't have to change a single line in the timing code past decoder (just something minor to make external/cached text subtitles display). I committed it immediately while avoiding thinking about it. But there really likely are subtle problems of all sorts. As far as I'm aware, gstreamer also supports backward playback. When I looked at this years ago, I couldn't find a way to actually try this, and I didn't revisit it now. Back then I also read talk slides from the person who implemented it, and I'm not sure if and which ideas I might have taken from it. It's possible that the timestamp reversal is inspired by it, but I didn't check. (I think it claimed that it could avoid large changes by changing a sign?) VapourSynth has some sort of reverse function, which provides a backward view on a video. The function itself is trivial to implement, as VapourSynth aims to provide random access to video by frame numbers (so you just request decreasing frame numbers). From what I remember, it wasn't exactly fluid, but it worked. It's implemented by creating an index, and seeking to the target on demand, and a bunch of caching. mpv could use it, but it would either require using VapourSynth as demuxer and decoder for everything, or replacing the current file every time something is supposed to be played backwards. FFmpeg's libavfilter has reversal filters for audio and video. These require buffering the entire media data of the file, and don't really fit into mpv's architecture. It could be used by playing a libavfilter graph that also demuxes, but that's like VapourSynth but worse.
2019-05-18 00:10:51 +00:00
pts = (pts * sub->sub_speed + opts->sub_delay) * sub->play_dir;
return pts;
}
static void wakeup_demux(void *ctx)
{
struct mp_dispatch_queue *q = ctx;
mp_dispatch_interrupt(q);
}
void sub_destroy(struct dec_sub *sub)
{
if (!sub)
return;
demux_set_stream_wakeup_cb(sub->sh, NULL, NULL);
if (sub->sd) {
sub_reset(sub);
sub->sd->driver->uninit(sub->sd);
}
talloc_free(sub->sd);
pthread_mutex_destroy(&sub->lock);
talloc_free(sub);
}
static struct sd *init_decoder(struct dec_sub *sub)
{
for (int n = 0; sd_list[n]; n++) {
const struct sd_functions *driver = sd_list[n];
struct sd *sd = talloc(NULL, struct sd);
*sd = (struct sd){
.global = sub->global,
.log = mp_log_new(sd, sub->log, driver->name),
.opts = sub->opts,
.driver = driver,
.attachments = sub->attachments,
.codec = sub->codec,
.preload_ok = true,
};
if (sd->driver->init(sd) >= 0)
return sd;
talloc_free(sd);
2013-06-23 22:47:08 +00:00
}
MP_ERR(sub, "Could not find subtitle decoder for format '%s'.\n",
sub->codec->codec);
return NULL;
}
// Thread-safety of the returned object: all functions are thread-safe,
// except sub_get_bitmaps() and sub_get_text(). Decoder backends (sd_*)
// do not need to acquire locks.
// Ownership of attachments goes to the callee, and is released with
// talloc_free() (even on failure).
struct dec_sub *sub_create(struct mpv_global *global, struct sh_stream *sh,
sub: align ytdl-hook secondary subs to the top 29e15e6248 prefixed youtube-dl's subs url with an edl prefix to not download them until they're selected, which is useful when there are many sub languages. But this prefix broke the alignment of secondary subs, which would overlap the primary subs instead of always being placed at the top. This can be tested with --sub-file='edl://!no_clip;!delay_open,media_type=sub;secondary_sub.srt' When a sub is added, sub.c:reinit_sub() is called. This calls in init_subdec() -> dec_sub.c:sub_create() -> init_decoder() -> sd_ass:init(). Then reinit_sub() calls sub_control(track->d_sub, SD_CTRL_SET_TOP, &(bool){!!order}) which sets sd_ass_priv.on_top = true for secondary subs. But for EDL subs the real sub is initialized again when in dec_sub.c:sub_read_packets() is_new_segment() returns true and update_segment() is called, or when sub_get_bitmaps() calls update_segment(). update_segment() then calls init_decoder(), which calls sd_ass:init(), so sd_ass_priv is reinitialized, and its on_top property is left false. This commit sets it to true again. For URLs that need to be downloaded it seems that the update_segment() call that reinitializes sd_ass_priv is always the one in sub_read_packets(), but with local subs sub_get_bitmaps() is usually called earlier (though there shouldn't be a reason to use the EDL URL for local subs), so I added the order parameter to sub_create(), rather than adding it to all of update_segment(), sub_read_packets() and sub_get_bitmaps(). Also removes the cast to bool in the other sub_control call, since sub/sd_ass.c:control already casts arg to bool when cmd is SD_CTRL_SET_TOP.
2021-08-10 20:11:53 +00:00
struct attachment_list *attachments, int order)
{
assert(sh && sh->type == STREAM_SUB);
struct dec_sub *sub = talloc(NULL, struct dec_sub);
*sub = (struct dec_sub){
.log = mp_log_new(sub, global->log, "sub"),
.global = global,
.opts_cache = m_config_cache_alloc(sub, global, &mp_subtitle_sub_opts),
.sh = sh,
.codec = sh->codec,
.attachments = talloc_steal(sub, attachments),
Implement backwards playback See manpage additions. This is a huge hack. You can bet there are shit tons of bugs. It's literally forcing square pegs into round holes. Hopefully, the manpage wall of text makes it clear enough that the whole shit can easily crash and burn. (Although it shouldn't literally crash. That would be a bug. It possibly _could_ start a fire by entering some sort of endless loop, not a literal one, just something where it tries to do work without making progress.) (Some obvious bugs I simply ignored for this initial version, but there's a number of potential bugs I can't even imagine. Normal playback should remain completely unaffected, though.) How this works is also described in the manpage. Basically, we demux in reverse, then we decode in reverse, then we render in reverse. The decoding part is the simplest: just reorder the decoder output. This weirdly integrates with the timeline/ordered chapter code, which also has special requirements on feeding the packets to the decoder in a non-straightforward way (it doesn't conflict, although a bugmessmass breaks correct slicing of segments, so EDL/ordered chapter playback is broken in backward direction). Backward demuxing is pretty involved. In theory, it could be much easier: simply iterating the usual demuxer output backward. But this just doesn't fit into our code, so there's a cthulhu nightmare of shit. To be specific, each stream (audio, video) is reversed separately. At least this means we can do backward playback within cached content (for example, you could play backwards in a live stream; on that note, it disables prefetching, which would lead to losing new live video, but this could be avoided). The fuckmess also meant that I didn't bother trying to support subtitles. Subtitles are a problem because they're "sparse" streams. They need to be "passively" demuxed: you don't try to read a subtitle packet, you demux audio and video, and then look whether there was a subtitle packet. This means to get subtitles for a time range, you need to know that you demuxed video and audio over this range, which becomes pretty messy when you demux audio and video backwards separately. Backward display is the most weird (and potentially buggy) part. To avoid that we need to touch a LOT of timing code, we negate all timestamps. The basic idea is that due to the navigation, all comparisons and subtractions of timestamps keep working, and you don't need to touch every single of them to "reverse" them. E.g.: bool before = pts_a < pts_b; would need to be: bool before = forward ? pts_a < pts_b : pts_a > pts_b; or: bool before = pts_a * dir < pts_b * dir; or if you, as it's implemented now, just do this after decoding: pts_a *= dir; pts_b *= dir; and then in the normal timing/renderer code: bool before = pts_a < pts_b; Consequently, we don't need many changes in the latter code. But some assumptions inhererently true for forward playback may have been broken anyway. What is mainly needed is fixing places where values are passed between positive and negative "domains". For example, seeking and timestamp user display always uses positive timestamps. The main mess is that it's not obvious which domain a given variable should or does use. Well, in my tests with a single file, it suddenly started to work when I did this. I'm honestly surprised that it did, and that I didn't have to change a single line in the timing code past decoder (just something minor to make external/cached text subtitles display). I committed it immediately while avoiding thinking about it. But there really likely are subtle problems of all sorts. As far as I'm aware, gstreamer also supports backward playback. When I looked at this years ago, I couldn't find a way to actually try this, and I didn't revisit it now. Back then I also read talk slides from the person who implemented it, and I'm not sure if and which ideas I might have taken from it. It's possible that the timestamp reversal is inspired by it, but I didn't check. (I think it claimed that it could avoid large changes by changing a sign?) VapourSynth has some sort of reverse function, which provides a backward view on a video. The function itself is trivial to implement, as VapourSynth aims to provide random access to video by frame numbers (so you just request decreasing frame numbers). From what I remember, it wasn't exactly fluid, but it worked. It's implemented by creating an index, and seeking to the target on demand, and a bunch of caching. mpv could use it, but it would either require using VapourSynth as demuxer and decoder for everything, or replacing the current file every time something is supposed to be played backwards. FFmpeg's libavfilter has reversal filters for audio and video. These require buffering the entire media data of the file, and don't really fit into mpv's architecture. It could be used by playing a libavfilter graph that also demuxes, but that's like VapourSynth but worse.
2019-05-18 00:10:51 +00:00
.play_dir = 1,
sub: align ytdl-hook secondary subs to the top 29e15e6248 prefixed youtube-dl's subs url with an edl prefix to not download them until they're selected, which is useful when there are many sub languages. But this prefix broke the alignment of secondary subs, which would overlap the primary subs instead of always being placed at the top. This can be tested with --sub-file='edl://!no_clip;!delay_open,media_type=sub;secondary_sub.srt' When a sub is added, sub.c:reinit_sub() is called. This calls in init_subdec() -> dec_sub.c:sub_create() -> init_decoder() -> sd_ass:init(). Then reinit_sub() calls sub_control(track->d_sub, SD_CTRL_SET_TOP, &(bool){!!order}) which sets sd_ass_priv.on_top = true for secondary subs. But for EDL subs the real sub is initialized again when in dec_sub.c:sub_read_packets() is_new_segment() returns true and update_segment() is called, or when sub_get_bitmaps() calls update_segment(). update_segment() then calls init_decoder(), which calls sd_ass:init(), so sd_ass_priv is reinitialized, and its on_top property is left false. This commit sets it to true again. For URLs that need to be downloaded it seems that the update_segment() call that reinitializes sd_ass_priv is always the one in sub_read_packets(), but with local subs sub_get_bitmaps() is usually called earlier (though there shouldn't be a reason to use the EDL URL for local subs), so I added the order parameter to sub_create(), rather than adding it to all of update_segment(), sub_read_packets() and sub_get_bitmaps(). Also removes the cast to bool in the other sub_control call, since sub/sd_ass.c:control already casts arg to bool when cmd is SD_CTRL_SET_TOP.
2021-08-10 20:11:53 +00:00
.order = order,
.last_pkt_pts = MP_NOPTS_VALUE,
Rewrite ordered chapters and timeline stuff This uses a different method to piece segments together. The old approach basically changes to a new file (with a new start offset) any time a segment ends. This meant waiting for audio/video end on segment end, and then changing to the new segment all at once. It had a very weird impact on the playback core, and some things (like truly gapless segment transitions, or frame backstepping) just didn't work. The new approach adds the demux_timeline pseudo-demuxer, which presents an uniform packet stream from the many segments. This is pretty similar to how ordered chapters are implemented everywhere else. It also reminds of the FFmpeg concat pseudo-demuxer. The "pure" version of this approach doesn't work though. Segments can actually have different codec configurations (different extradata), and subtitles are most likely broken too. (Subtitles have multiple corner cases which break the pure stream-concatenation approach completely.) To counter this, we do two things: - Reinit the decoder with each segment. We go as far as allowing concatenating files with completely different codecs for the sake of EDL (which also uses the timeline infrastructure). A "lighter" approach would try to make use of decoder mechanism to update e.g. the extradata, but that seems fragile. - Clip decoded data to segment boundaries. This is equivalent to normal playback core mechanisms like hr-seek, but now the playback core doesn't need to care about these things. These two mechanisms are equivalent to what happened in the old implementation, except they don't happen in the playback core anymore. In other words, the playback core is completely relieved from timeline implementation details. (Which honestly is exactly what I'm trying to do here. I don't think ordered chapter behavior deserves improvement, even if it's bad - but I want to get it out from the playback core.) There is code duplication between audio and video decoder common code. This is awful and could be shareable - but this will happen later. Note that the audio path has some code to clip audio frames for the purpose of codec preroll/gapless handling, but it's not shared as sharing it would cause more pain than it would help.
2016-02-15 20:04:07 +00:00
.last_vo_pts = MP_NOPTS_VALUE,
.start = MP_NOPTS_VALUE,
.end = MP_NOPTS_VALUE,
};
sub->opts = sub->opts_cache->opts;
mpthread_mutex_init_recursive(&sub->lock);
sub->sd = init_decoder(sub);
if (sub->sd) {
update_subtitle_speed(sub);
return sub;
}
sub_destroy(sub);
return NULL;
2013-06-23 22:47:08 +00:00
}
Rewrite ordered chapters and timeline stuff This uses a different method to piece segments together. The old approach basically changes to a new file (with a new start offset) any time a segment ends. This meant waiting for audio/video end on segment end, and then changing to the new segment all at once. It had a very weird impact on the playback core, and some things (like truly gapless segment transitions, or frame backstepping) just didn't work. The new approach adds the demux_timeline pseudo-demuxer, which presents an uniform packet stream from the many segments. This is pretty similar to how ordered chapters are implemented everywhere else. It also reminds of the FFmpeg concat pseudo-demuxer. The "pure" version of this approach doesn't work though. Segments can actually have different codec configurations (different extradata), and subtitles are most likely broken too. (Subtitles have multiple corner cases which break the pure stream-concatenation approach completely.) To counter this, we do two things: - Reinit the decoder with each segment. We go as far as allowing concatenating files with completely different codecs for the sake of EDL (which also uses the timeline infrastructure). A "lighter" approach would try to make use of decoder mechanism to update e.g. the extradata, but that seems fragile. - Clip decoded data to segment boundaries. This is equivalent to normal playback core mechanisms like hr-seek, but now the playback core doesn't need to care about these things. These two mechanisms are equivalent to what happened in the old implementation, except they don't happen in the playback core anymore. In other words, the playback core is completely relieved from timeline implementation details. (Which honestly is exactly what I'm trying to do here. I don't think ordered chapter behavior deserves improvement, even if it's bad - but I want to get it out from the playback core.) There is code duplication between audio and video decoder common code. This is awful and could be shareable - but this will happen later. Note that the audio path has some code to clip audio frames for the purpose of codec preroll/gapless handling, but it's not shared as sharing it would cause more pain than it would help.
2016-02-15 20:04:07 +00:00
// Called locked.
static void update_segment(struct dec_sub *sub)
{
if (sub->new_segment && sub->last_vo_pts != MP_NOPTS_VALUE &&
sub->last_vo_pts >= sub->new_segment->start)
{
MP_VERBOSE(sub, "Switch segment: %f at %f\n", sub->new_segment->start,
sub->last_vo_pts);
Rewrite ordered chapters and timeline stuff This uses a different method to piece segments together. The old approach basically changes to a new file (with a new start offset) any time a segment ends. This meant waiting for audio/video end on segment end, and then changing to the new segment all at once. It had a very weird impact on the playback core, and some things (like truly gapless segment transitions, or frame backstepping) just didn't work. The new approach adds the demux_timeline pseudo-demuxer, which presents an uniform packet stream from the many segments. This is pretty similar to how ordered chapters are implemented everywhere else. It also reminds of the FFmpeg concat pseudo-demuxer. The "pure" version of this approach doesn't work though. Segments can actually have different codec configurations (different extradata), and subtitles are most likely broken too. (Subtitles have multiple corner cases which break the pure stream-concatenation approach completely.) To counter this, we do two things: - Reinit the decoder with each segment. We go as far as allowing concatenating files with completely different codecs for the sake of EDL (which also uses the timeline infrastructure). A "lighter" approach would try to make use of decoder mechanism to update e.g. the extradata, but that seems fragile. - Clip decoded data to segment boundaries. This is equivalent to normal playback core mechanisms like hr-seek, but now the playback core doesn't need to care about these things. These two mechanisms are equivalent to what happened in the old implementation, except they don't happen in the playback core anymore. In other words, the playback core is completely relieved from timeline implementation details. (Which honestly is exactly what I'm trying to do here. I don't think ordered chapter behavior deserves improvement, even if it's bad - but I want to get it out from the playback core.) There is code duplication between audio and video decoder common code. This is awful and could be shareable - but this will happen later. Note that the audio path has some code to clip audio frames for the purpose of codec preroll/gapless handling, but it's not shared as sharing it would cause more pain than it would help.
2016-02-15 20:04:07 +00:00
sub->codec = sub->new_segment->codec;
sub->start = sub->new_segment->start;
sub->end = sub->new_segment->end;
struct sd *new = init_decoder(sub);
if (new) {
sub->sd->driver->uninit(sub->sd);
talloc_free(sub->sd);
sub->sd = new;
update_subtitle_speed(sub);
sub: align ytdl-hook secondary subs to the top 29e15e6248 prefixed youtube-dl's subs url with an edl prefix to not download them until they're selected, which is useful when there are many sub languages. But this prefix broke the alignment of secondary subs, which would overlap the primary subs instead of always being placed at the top. This can be tested with --sub-file='edl://!no_clip;!delay_open,media_type=sub;secondary_sub.srt' When a sub is added, sub.c:reinit_sub() is called. This calls in init_subdec() -> dec_sub.c:sub_create() -> init_decoder() -> sd_ass:init(). Then reinit_sub() calls sub_control(track->d_sub, SD_CTRL_SET_TOP, &(bool){!!order}) which sets sd_ass_priv.on_top = true for secondary subs. But for EDL subs the real sub is initialized again when in dec_sub.c:sub_read_packets() is_new_segment() returns true and update_segment() is called, or when sub_get_bitmaps() calls update_segment(). update_segment() then calls init_decoder(), which calls sd_ass:init(), so sd_ass_priv is reinitialized, and its on_top property is left false. This commit sets it to true again. For URLs that need to be downloaded it seems that the update_segment() call that reinitializes sd_ass_priv is always the one in sub_read_packets(), but with local subs sub_get_bitmaps() is usually called earlier (though there shouldn't be a reason to use the EDL URL for local subs), so I added the order parameter to sub_create(), rather than adding it to all of update_segment(), sub_read_packets() and sub_get_bitmaps(). Also removes the cast to bool in the other sub_control call, since sub/sd_ass.c:control already casts arg to bool when cmd is SD_CTRL_SET_TOP.
2021-08-10 20:11:53 +00:00
sub_control(sub, SD_CTRL_SET_TOP, &sub->order);
Rewrite ordered chapters and timeline stuff This uses a different method to piece segments together. The old approach basically changes to a new file (with a new start offset) any time a segment ends. This meant waiting for audio/video end on segment end, and then changing to the new segment all at once. It had a very weird impact on the playback core, and some things (like truly gapless segment transitions, or frame backstepping) just didn't work. The new approach adds the demux_timeline pseudo-demuxer, which presents an uniform packet stream from the many segments. This is pretty similar to how ordered chapters are implemented everywhere else. It also reminds of the FFmpeg concat pseudo-demuxer. The "pure" version of this approach doesn't work though. Segments can actually have different codec configurations (different extradata), and subtitles are most likely broken too. (Subtitles have multiple corner cases which break the pure stream-concatenation approach completely.) To counter this, we do two things: - Reinit the decoder with each segment. We go as far as allowing concatenating files with completely different codecs for the sake of EDL (which also uses the timeline infrastructure). A "lighter" approach would try to make use of decoder mechanism to update e.g. the extradata, but that seems fragile. - Clip decoded data to segment boundaries. This is equivalent to normal playback core mechanisms like hr-seek, but now the playback core doesn't need to care about these things. These two mechanisms are equivalent to what happened in the old implementation, except they don't happen in the playback core anymore. In other words, the playback core is completely relieved from timeline implementation details. (Which honestly is exactly what I'm trying to do here. I don't think ordered chapter behavior deserves improvement, even if it's bad - but I want to get it out from the playback core.) There is code duplication between audio and video decoder common code. This is awful and could be shareable - but this will happen later. Note that the audio path has some code to clip audio frames for the purpose of codec preroll/gapless handling, but it's not shared as sharing it would cause more pain than it would help.
2016-02-15 20:04:07 +00:00
} else {
// We'll just keep the current decoder, and feed it possibly
// invalid data (not our fault if it crashes or something).
MP_ERR(sub, "Can't change to new codec.\n");
}
sub->sd->driver->decode(sub->sd, sub->new_segment);
talloc_free(sub->new_segment);
sub->new_segment = NULL;
}
}
bool sub_can_preload(struct dec_sub *sub)
{
bool r;
pthread_mutex_lock(&sub->lock);
r = sub->sd->driver->accept_packets_in_advance && !sub->preload_attempted;
pthread_mutex_unlock(&sub->lock);
return r;
}
void sub_preload(struct dec_sub *sub)
{
pthread_mutex_lock(&sub->lock);
struct mp_dispatch_queue *demux_waiter = mp_dispatch_create(NULL);
demux_set_stream_wakeup_cb(sub->sh, wakeup_demux, demux_waiter);
sub->preload_attempted = true;
for (;;) {
struct demux_packet *pkt = NULL;
int r = demux_read_packet_async(sub->sh, &pkt);
if (r == 0) {
mp_dispatch_queue_process(demux_waiter, INFINITY);
continue;
}
if (!pkt)
break;
sub->sd->driver->decode(sub->sd, pkt);
talloc_free(pkt);
}
demux_set_stream_wakeup_cb(sub->sh, NULL, NULL);
talloc_free(demux_waiter);
pthread_mutex_unlock(&sub->lock);
}
static bool is_new_segment(struct dec_sub *sub, struct demux_packet *p)
{
return p->segmented &&
(p->start != sub->start || p->end != sub->end || p->codec != sub->codec);
}
// Read packets from the demuxer stream passed to sub_create(). Return true if
// enough packets were read, false if the player should wait until the demuxer
// signals new packets available (and then should retry).
bool sub_read_packets(struct dec_sub *sub, double video_pts)
{
bool r = true;
pthread_mutex_lock(&sub->lock);
video_pts = pts_to_subtitle(sub, video_pts);
while (1) {
bool read_more = true;
if (sub->sd->driver->accepts_packet)
read_more = sub->sd->driver->accepts_packet(sub->sd, video_pts);
if (!read_more)
break;
if (sub->new_segment && sub->new_segment->start < video_pts) {
sub->last_vo_pts = video_pts;
update_segment(sub);
}
Rewrite ordered chapters and timeline stuff This uses a different method to piece segments together. The old approach basically changes to a new file (with a new start offset) any time a segment ends. This meant waiting for audio/video end on segment end, and then changing to the new segment all at once. It had a very weird impact on the playback core, and some things (like truly gapless segment transitions, or frame backstepping) just didn't work. The new approach adds the demux_timeline pseudo-demuxer, which presents an uniform packet stream from the many segments. This is pretty similar to how ordered chapters are implemented everywhere else. It also reminds of the FFmpeg concat pseudo-demuxer. The "pure" version of this approach doesn't work though. Segments can actually have different codec configurations (different extradata), and subtitles are most likely broken too. (Subtitles have multiple corner cases which break the pure stream-concatenation approach completely.) To counter this, we do two things: - Reinit the decoder with each segment. We go as far as allowing concatenating files with completely different codecs for the sake of EDL (which also uses the timeline infrastructure). A "lighter" approach would try to make use of decoder mechanism to update e.g. the extradata, but that seems fragile. - Clip decoded data to segment boundaries. This is equivalent to normal playback core mechanisms like hr-seek, but now the playback core doesn't need to care about these things. These two mechanisms are equivalent to what happened in the old implementation, except they don't happen in the playback core anymore. In other words, the playback core is completely relieved from timeline implementation details. (Which honestly is exactly what I'm trying to do here. I don't think ordered chapter behavior deserves improvement, even if it's bad - but I want to get it out from the playback core.) There is code duplication between audio and video decoder common code. This is awful and could be shareable - but this will happen later. Note that the audio path has some code to clip audio frames for the purpose of codec preroll/gapless handling, but it's not shared as sharing it would cause more pain than it would help.
2016-02-15 20:04:07 +00:00
if (sub->new_segment)
break;
// (Use this mechanism only if sub_delay matters to avoid corner cases.)
double min_pts = sub->opts->sub_delay < 0 ? video_pts : MP_NOPTS_VALUE;
struct demux_packet *pkt;
int st = demux_read_packet_async_until(sub->sh, min_pts, &pkt);
// Note: "wait" (st==0) happens with non-interleaved streams only, and
// then we should stop the playloop until a new enough packet has been
// seen (or the subtitle decoder's queue is full). This usually does not
// happen for interleaved subtitle streams, which never return "wait"
// when reading, unless min_pts is set.
if (st <= 0) {
r = st < 0 || (sub->last_pkt_pts != MP_NOPTS_VALUE &&
sub->last_pkt_pts > video_pts);
break;
}
if (sub->recorder_sink)
mp_recorder_feed_packet(sub->recorder_sink, pkt);
sub->last_pkt_pts = pkt->pts;
Rewrite ordered chapters and timeline stuff This uses a different method to piece segments together. The old approach basically changes to a new file (with a new start offset) any time a segment ends. This meant waiting for audio/video end on segment end, and then changing to the new segment all at once. It had a very weird impact on the playback core, and some things (like truly gapless segment transitions, or frame backstepping) just didn't work. The new approach adds the demux_timeline pseudo-demuxer, which presents an uniform packet stream from the many segments. This is pretty similar to how ordered chapters are implemented everywhere else. It also reminds of the FFmpeg concat pseudo-demuxer. The "pure" version of this approach doesn't work though. Segments can actually have different codec configurations (different extradata), and subtitles are most likely broken too. (Subtitles have multiple corner cases which break the pure stream-concatenation approach completely.) To counter this, we do two things: - Reinit the decoder with each segment. We go as far as allowing concatenating files with completely different codecs for the sake of EDL (which also uses the timeline infrastructure). A "lighter" approach would try to make use of decoder mechanism to update e.g. the extradata, but that seems fragile. - Clip decoded data to segment boundaries. This is equivalent to normal playback core mechanisms like hr-seek, but now the playback core doesn't need to care about these things. These two mechanisms are equivalent to what happened in the old implementation, except they don't happen in the playback core anymore. In other words, the playback core is completely relieved from timeline implementation details. (Which honestly is exactly what I'm trying to do here. I don't think ordered chapter behavior deserves improvement, even if it's bad - but I want to get it out from the playback core.) There is code duplication between audio and video decoder common code. This is awful and could be shareable - but this will happen later. Note that the audio path has some code to clip audio frames for the purpose of codec preroll/gapless handling, but it's not shared as sharing it would cause more pain than it would help.
2016-02-15 20:04:07 +00:00
if (is_new_segment(sub, pkt)) {
Rewrite ordered chapters and timeline stuff This uses a different method to piece segments together. The old approach basically changes to a new file (with a new start offset) any time a segment ends. This meant waiting for audio/video end on segment end, and then changing to the new segment all at once. It had a very weird impact on the playback core, and some things (like truly gapless segment transitions, or frame backstepping) just didn't work. The new approach adds the demux_timeline pseudo-demuxer, which presents an uniform packet stream from the many segments. This is pretty similar to how ordered chapters are implemented everywhere else. It also reminds of the FFmpeg concat pseudo-demuxer. The "pure" version of this approach doesn't work though. Segments can actually have different codec configurations (different extradata), and subtitles are most likely broken too. (Subtitles have multiple corner cases which break the pure stream-concatenation approach completely.) To counter this, we do two things: - Reinit the decoder with each segment. We go as far as allowing concatenating files with completely different codecs for the sake of EDL (which also uses the timeline infrastructure). A "lighter" approach would try to make use of decoder mechanism to update e.g. the extradata, but that seems fragile. - Clip decoded data to segment boundaries. This is equivalent to normal playback core mechanisms like hr-seek, but now the playback core doesn't need to care about these things. These two mechanisms are equivalent to what happened in the old implementation, except they don't happen in the playback core anymore. In other words, the playback core is completely relieved from timeline implementation details. (Which honestly is exactly what I'm trying to do here. I don't think ordered chapter behavior deserves improvement, even if it's bad - but I want to get it out from the playback core.) There is code duplication between audio and video decoder common code. This is awful and could be shareable - but this will happen later. Note that the audio path has some code to clip audio frames for the purpose of codec preroll/gapless handling, but it's not shared as sharing it would cause more pain than it would help.
2016-02-15 20:04:07 +00:00
sub->new_segment = pkt;
// Note that this can be delayed to a much later point in time.
update_segment(sub);
break;
}
if (!(sub->preload_attempted && sub->sd->preload_ok))
sub->sd->driver->decode(sub->sd, pkt);
talloc_free(pkt);
}
pthread_mutex_unlock(&sub->lock);
return r;
}
video: make OSD/subtitle bitmaps refcounted (sort of) Making OSD/subtitle bitmaps refcounted was planend a longer time ago, e.g. the sub_bitmaps.packed field (which refcounts the subtitle bitmap data) was added in 2016. But nothing benefited much from it, because struct sub_bitmaps was usually stack allocated, and there was this weird callback stuff through osd_draw(). Make it possible to get actually refcounted subtitle bitmaps on the OSD API level. For this, we just copy all subtitle data other than the bitmaps with sub_bitmaps_copy(). At first, I had planned some fancy refcount shit, but when that was a big mess and hard to debug and just boiled to emulating malloc(), I made it a full allocation+copy. This affects mostly the parts array. With crazy ASS subtitles, this parts array can get pretty big (thousands of elements or more), in which case the extra alloc/copy could become performance relevant. But then again this is just pure bullshit, and I see no need to care. In practice, this extra work most likely gets drowned out by libass murdering a single core (while mpv is waiting for it) anyway. So fuck it. I just wanted this so draw_bmp.c requires only a single call to render everything. VOs also can benefit from this, because the weird callback shit isn't necessary anymore (simpler code), but I haven't done anything about it yet. In general I'd hope this will work towards simplifying the OSD layer, which is prerequisite for making actual further improvements. I haven't tested some cases such as the "overlay-add" command. Maybe it crashes now? Who knows, who cares. In addition, it might be worthwhile to reduce the code duplication between all the things that output subtitle bitmaps (with repacking, image allocation, etc.), but that's orthogonal.
2020-04-26 21:34:32 +00:00
// Unref sub_bitmaps.rc to free the result. May return NULL.
struct sub_bitmaps *sub_get_bitmaps(struct dec_sub *sub, struct mp_osd_res dim,
int format, double pts)
{
video: make OSD/subtitle bitmaps refcounted (sort of) Making OSD/subtitle bitmaps refcounted was planend a longer time ago, e.g. the sub_bitmaps.packed field (which refcounts the subtitle bitmap data) was added in 2016. But nothing benefited much from it, because struct sub_bitmaps was usually stack allocated, and there was this weird callback stuff through osd_draw(). Make it possible to get actually refcounted subtitle bitmaps on the OSD API level. For this, we just copy all subtitle data other than the bitmaps with sub_bitmaps_copy(). At first, I had planned some fancy refcount shit, but when that was a big mess and hard to debug and just boiled to emulating malloc(), I made it a full allocation+copy. This affects mostly the parts array. With crazy ASS subtitles, this parts array can get pretty big (thousands of elements or more), in which case the extra alloc/copy could become performance relevant. But then again this is just pure bullshit, and I see no need to care. In practice, this extra work most likely gets drowned out by libass murdering a single core (while mpv is waiting for it) anyway. So fuck it. I just wanted this so draw_bmp.c requires only a single call to render everything. VOs also can benefit from this, because the weird callback shit isn't necessary anymore (simpler code), but I haven't done anything about it yet. In general I'd hope this will work towards simplifying the OSD layer, which is prerequisite for making actual further improvements. I haven't tested some cases such as the "overlay-add" command. Maybe it crashes now? Who knows, who cares. In addition, it might be worthwhile to reduce the code duplication between all the things that output subtitle bitmaps (with repacking, image allocation, etc.), but that's orthogonal.
2020-04-26 21:34:32 +00:00
pthread_mutex_lock(&sub->lock);
struct mp_subtitle_opts *opts = sub->opts;
pts = pts_to_subtitle(sub, pts);
Rewrite ordered chapters and timeline stuff This uses a different method to piece segments together. The old approach basically changes to a new file (with a new start offset) any time a segment ends. This meant waiting for audio/video end on segment end, and then changing to the new segment all at once. It had a very weird impact on the playback core, and some things (like truly gapless segment transitions, or frame backstepping) just didn't work. The new approach adds the demux_timeline pseudo-demuxer, which presents an uniform packet stream from the many segments. This is pretty similar to how ordered chapters are implemented everywhere else. It also reminds of the FFmpeg concat pseudo-demuxer. The "pure" version of this approach doesn't work though. Segments can actually have different codec configurations (different extradata), and subtitles are most likely broken too. (Subtitles have multiple corner cases which break the pure stream-concatenation approach completely.) To counter this, we do two things: - Reinit the decoder with each segment. We go as far as allowing concatenating files with completely different codecs for the sake of EDL (which also uses the timeline infrastructure). A "lighter" approach would try to make use of decoder mechanism to update e.g. the extradata, but that seems fragile. - Clip decoded data to segment boundaries. This is equivalent to normal playback core mechanisms like hr-seek, but now the playback core doesn't need to care about these things. These two mechanisms are equivalent to what happened in the old implementation, except they don't happen in the playback core anymore. In other words, the playback core is completely relieved from timeline implementation details. (Which honestly is exactly what I'm trying to do here. I don't think ordered chapter behavior deserves improvement, even if it's bad - but I want to get it out from the playback core.) There is code duplication between audio and video decoder common code. This is awful and could be shareable - but this will happen later. Note that the audio path has some code to clip audio frames for the purpose of codec preroll/gapless handling, but it's not shared as sharing it would cause more pain than it would help.
2016-02-15 20:04:07 +00:00
sub->last_vo_pts = pts;
update_segment(sub);
video: make OSD/subtitle bitmaps refcounted (sort of) Making OSD/subtitle bitmaps refcounted was planend a longer time ago, e.g. the sub_bitmaps.packed field (which refcounts the subtitle bitmap data) was added in 2016. But nothing benefited much from it, because struct sub_bitmaps was usually stack allocated, and there was this weird callback stuff through osd_draw(). Make it possible to get actually refcounted subtitle bitmaps on the OSD API level. For this, we just copy all subtitle data other than the bitmaps with sub_bitmaps_copy(). At first, I had planned some fancy refcount shit, but when that was a big mess and hard to debug and just boiled to emulating malloc(), I made it a full allocation+copy. This affects mostly the parts array. With crazy ASS subtitles, this parts array can get pretty big (thousands of elements or more), in which case the extra alloc/copy could become performance relevant. But then again this is just pure bullshit, and I see no need to care. In practice, this extra work most likely gets drowned out by libass murdering a single core (while mpv is waiting for it) anyway. So fuck it. I just wanted this so draw_bmp.c requires only a single call to render everything. VOs also can benefit from this, because the weird callback shit isn't necessary anymore (simpler code), but I haven't done anything about it yet. In general I'd hope this will work towards simplifying the OSD layer, which is prerequisite for making actual further improvements. I haven't tested some cases such as the "overlay-add" command. Maybe it crashes now? Who knows, who cares. In addition, it might be worthwhile to reduce the code duplication between all the things that output subtitle bitmaps (with repacking, image allocation, etc.), but that's orthogonal.
2020-04-26 21:34:32 +00:00
struct sub_bitmaps *res = NULL;
if (!(sub->end != MP_NOPTS_VALUE && pts >= sub->end) &&
opts->sub_visibility && sub->sd->driver->get_bitmaps)
res = sub->sd->driver->get_bitmaps(sub->sd, dim, format, pts);
video: make OSD/subtitle bitmaps refcounted (sort of) Making OSD/subtitle bitmaps refcounted was planend a longer time ago, e.g. the sub_bitmaps.packed field (which refcounts the subtitle bitmap data) was added in 2016. But nothing benefited much from it, because struct sub_bitmaps was usually stack allocated, and there was this weird callback stuff through osd_draw(). Make it possible to get actually refcounted subtitle bitmaps on the OSD API level. For this, we just copy all subtitle data other than the bitmaps with sub_bitmaps_copy(). At first, I had planned some fancy refcount shit, but when that was a big mess and hard to debug and just boiled to emulating malloc(), I made it a full allocation+copy. This affects mostly the parts array. With crazy ASS subtitles, this parts array can get pretty big (thousands of elements or more), in which case the extra alloc/copy could become performance relevant. But then again this is just pure bullshit, and I see no need to care. In practice, this extra work most likely gets drowned out by libass murdering a single core (while mpv is waiting for it) anyway. So fuck it. I just wanted this so draw_bmp.c requires only a single call to render everything. VOs also can benefit from this, because the weird callback shit isn't necessary anymore (simpler code), but I haven't done anything about it yet. In general I'd hope this will work towards simplifying the OSD layer, which is prerequisite for making actual further improvements. I haven't tested some cases such as the "overlay-add" command. Maybe it crashes now? Who knows, who cares. In addition, it might be worthwhile to reduce the code duplication between all the things that output subtitle bitmaps (with repacking, image allocation, etc.), but that's orthogonal.
2020-04-26 21:34:32 +00:00
pthread_mutex_unlock(&sub->lock);
return res;
}
// The returned string is talloc'ed.
char *sub_get_text(struct dec_sub *sub, double pts, enum sd_text_type type)
{
pthread_mutex_lock(&sub->lock);
char *text = NULL;
Rewrite ordered chapters and timeline stuff This uses a different method to piece segments together. The old approach basically changes to a new file (with a new start offset) any time a segment ends. This meant waiting for audio/video end on segment end, and then changing to the new segment all at once. It had a very weird impact on the playback core, and some things (like truly gapless segment transitions, or frame backstepping) just didn't work. The new approach adds the demux_timeline pseudo-demuxer, which presents an uniform packet stream from the many segments. This is pretty similar to how ordered chapters are implemented everywhere else. It also reminds of the FFmpeg concat pseudo-demuxer. The "pure" version of this approach doesn't work though. Segments can actually have different codec configurations (different extradata), and subtitles are most likely broken too. (Subtitles have multiple corner cases which break the pure stream-concatenation approach completely.) To counter this, we do two things: - Reinit the decoder with each segment. We go as far as allowing concatenating files with completely different codecs for the sake of EDL (which also uses the timeline infrastructure). A "lighter" approach would try to make use of decoder mechanism to update e.g. the extradata, but that seems fragile. - Clip decoded data to segment boundaries. This is equivalent to normal playback core mechanisms like hr-seek, but now the playback core doesn't need to care about these things. These two mechanisms are equivalent to what happened in the old implementation, except they don't happen in the playback core anymore. In other words, the playback core is completely relieved from timeline implementation details. (Which honestly is exactly what I'm trying to do here. I don't think ordered chapter behavior deserves improvement, even if it's bad - but I want to get it out from the playback core.) There is code duplication between audio and video decoder common code. This is awful and could be shareable - but this will happen later. Note that the audio path has some code to clip audio frames for the purpose of codec preroll/gapless handling, but it's not shared as sharing it would cause more pain than it would help.
2016-02-15 20:04:07 +00:00
pts = pts_to_subtitle(sub, pts);
Rewrite ordered chapters and timeline stuff This uses a different method to piece segments together. The old approach basically changes to a new file (with a new start offset) any time a segment ends. This meant waiting for audio/video end on segment end, and then changing to the new segment all at once. It had a very weird impact on the playback core, and some things (like truly gapless segment transitions, or frame backstepping) just didn't work. The new approach adds the demux_timeline pseudo-demuxer, which presents an uniform packet stream from the many segments. This is pretty similar to how ordered chapters are implemented everywhere else. It also reminds of the FFmpeg concat pseudo-demuxer. The "pure" version of this approach doesn't work though. Segments can actually have different codec configurations (different extradata), and subtitles are most likely broken too. (Subtitles have multiple corner cases which break the pure stream-concatenation approach completely.) To counter this, we do two things: - Reinit the decoder with each segment. We go as far as allowing concatenating files with completely different codecs for the sake of EDL (which also uses the timeline infrastructure). A "lighter" approach would try to make use of decoder mechanism to update e.g. the extradata, but that seems fragile. - Clip decoded data to segment boundaries. This is equivalent to normal playback core mechanisms like hr-seek, but now the playback core doesn't need to care about these things. These two mechanisms are equivalent to what happened in the old implementation, except they don't happen in the playback core anymore. In other words, the playback core is completely relieved from timeline implementation details. (Which honestly is exactly what I'm trying to do here. I don't think ordered chapter behavior deserves improvement, even if it's bad - but I want to get it out from the playback core.) There is code duplication between audio and video decoder common code. This is awful and could be shareable - but this will happen later. Note that the audio path has some code to clip audio frames for the purpose of codec preroll/gapless handling, but it's not shared as sharing it would cause more pain than it would help.
2016-02-15 20:04:07 +00:00
sub->last_vo_pts = pts;
update_segment(sub);
if (sub->sd->driver->get_text)
text = sub->sd->driver->get_text(sub->sd, pts, type);
pthread_mutex_unlock(&sub->lock);
return text;
}
struct sd_times sub_get_times(struct dec_sub *sub, double pts)
{
pthread_mutex_lock(&sub->lock);
struct sd_times res = { .start = MP_NOPTS_VALUE, .end = MP_NOPTS_VALUE };
pts = pts_to_subtitle(sub, pts);
sub->last_vo_pts = pts;
update_segment(sub);
if (sub->sd->driver->get_times)
res = sub->sd->driver->get_times(sub->sd, pts);
pthread_mutex_unlock(&sub->lock);
return res;
}
void sub_reset(struct dec_sub *sub)
{
pthread_mutex_lock(&sub->lock);
if (sub->sd->driver->reset)
sub->sd->driver->reset(sub->sd);
sub->last_pkt_pts = MP_NOPTS_VALUE;
Rewrite ordered chapters and timeline stuff This uses a different method to piece segments together. The old approach basically changes to a new file (with a new start offset) any time a segment ends. This meant waiting for audio/video end on segment end, and then changing to the new segment all at once. It had a very weird impact on the playback core, and some things (like truly gapless segment transitions, or frame backstepping) just didn't work. The new approach adds the demux_timeline pseudo-demuxer, which presents an uniform packet stream from the many segments. This is pretty similar to how ordered chapters are implemented everywhere else. It also reminds of the FFmpeg concat pseudo-demuxer. The "pure" version of this approach doesn't work though. Segments can actually have different codec configurations (different extradata), and subtitles are most likely broken too. (Subtitles have multiple corner cases which break the pure stream-concatenation approach completely.) To counter this, we do two things: - Reinit the decoder with each segment. We go as far as allowing concatenating files with completely different codecs for the sake of EDL (which also uses the timeline infrastructure). A "lighter" approach would try to make use of decoder mechanism to update e.g. the extradata, but that seems fragile. - Clip decoded data to segment boundaries. This is equivalent to normal playback core mechanisms like hr-seek, but now the playback core doesn't need to care about these things. These two mechanisms are equivalent to what happened in the old implementation, except they don't happen in the playback core anymore. In other words, the playback core is completely relieved from timeline implementation details. (Which honestly is exactly what I'm trying to do here. I don't think ordered chapter behavior deserves improvement, even if it's bad - but I want to get it out from the playback core.) There is code duplication between audio and video decoder common code. This is awful and could be shareable - but this will happen later. Note that the audio path has some code to clip audio frames for the purpose of codec preroll/gapless handling, but it's not shared as sharing it would cause more pain than it would help.
2016-02-15 20:04:07 +00:00
sub->last_vo_pts = MP_NOPTS_VALUE;
talloc_free(sub->new_segment);
sub->new_segment = NULL;
pthread_mutex_unlock(&sub->lock);
}
void sub_select(struct dec_sub *sub, bool selected)
{
pthread_mutex_lock(&sub->lock);
if (sub->sd->driver->select)
sub->sd->driver->select(sub->sd, selected);
pthread_mutex_unlock(&sub->lock);
}
int sub_control(struct dec_sub *sub, enum sd_ctrl cmd, void *arg)
{
int r = CONTROL_UNKNOWN;
pthread_mutex_lock(&sub->lock);
sub: make filter_sdh a "proper" filter, allow runtime changes Until now, filter_sdh was simply a function that was called by sd_ass directly (if enabled). I want to add another filter, so it's time to turn this into a somewhat more general subtitle filtering infrastructure. I pondered whether to reuse the audio/video filtering stuff - but better not. Also, since subtitles are horrible and tend to refuse proper abstraction, it's still messed into sd_ass, instead of working on the dec_sub.c level. Actually mpv used to have subtitle "filters" and even made subtitle converters part of it, but it was fairly horrible, so don't do that again. In addition, make runtime changes possible. Since this was supposed to be a quick hack, I just decided to put all subtitle filter options into a separate option group (=> simpler change notification), to manually push the change through the playloop (like it was sort of before for OSD options), and to recreate the sub filter chain completely in every change. Should be good enough. One strangeness is that due to prefetching and such, most subtitle packets (or those some time ahead) are actually done filtering when we change, so the user still needs to manually seek to actually refresh everything. And since subtitle data is usually cached in ASS_Track (for other terrible but user-friendly reasons), we also must clear the subtitle data, but of course only on seek, since otherwise all subtitles would just disappear. What a fucking mess, but such is life. We could trigger a "refresh seek" to make this more automatic, but I don't feel like it currently. This is slightly inefficient (lots of allocations and copying), but I decided that it doesn't matter. Could matter slightly for crazy ASS subtitles that render with thousands of events. Not very well tested. Still seems to work, but I didn't have many test cases.
2020-02-16 00:02:17 +00:00
bool propagate = false;
switch (cmd) {
case SD_CTRL_SET_VIDEO_DEF_FPS:
sub->video_fps = *(double *)arg;
update_subtitle_speed(sub);
break;
case SD_CTRL_SUB_STEP: {
double *a = arg;
double arg2[2] = {a[0], a[1]};
arg2[0] = pts_to_subtitle(sub, arg2[0]);
if (sub->sd->driver->control)
r = sub->sd->driver->control(sub->sd, cmd, arg2);
if (r == CONTROL_OK)
a[0] = pts_from_subtitle(sub, arg2[0]);
break;
sub: make filter_sdh a "proper" filter, allow runtime changes Until now, filter_sdh was simply a function that was called by sd_ass directly (if enabled). I want to add another filter, so it's time to turn this into a somewhat more general subtitle filtering infrastructure. I pondered whether to reuse the audio/video filtering stuff - but better not. Also, since subtitles are horrible and tend to refuse proper abstraction, it's still messed into sd_ass, instead of working on the dec_sub.c level. Actually mpv used to have subtitle "filters" and even made subtitle converters part of it, but it was fairly horrible, so don't do that again. In addition, make runtime changes possible. Since this was supposed to be a quick hack, I just decided to put all subtitle filter options into a separate option group (=> simpler change notification), to manually push the change through the playloop (like it was sort of before for OSD options), and to recreate the sub filter chain completely in every change. Should be good enough. One strangeness is that due to prefetching and such, most subtitle packets (or those some time ahead) are actually done filtering when we change, so the user still needs to manually seek to actually refresh everything. And since subtitle data is usually cached in ASS_Track (for other terrible but user-friendly reasons), we also must clear the subtitle data, but of course only on seek, since otherwise all subtitles would just disappear. What a fucking mess, but such is life. We could trigger a "refresh seek" to make this more automatic, but I don't feel like it currently. This is slightly inefficient (lots of allocations and copying), but I decided that it doesn't matter. Could matter slightly for crazy ASS subtitles that render with thousands of events. Not very well tested. Still seems to work, but I didn't have many test cases.
2020-02-16 00:02:17 +00:00
case SD_CTRL_UPDATE_OPTS:
if (m_config_cache_update(sub->opts_cache))
update_subtitle_speed(sub);
propagate = true;
break;
}
default:
sub: make filter_sdh a "proper" filter, allow runtime changes Until now, filter_sdh was simply a function that was called by sd_ass directly (if enabled). I want to add another filter, so it's time to turn this into a somewhat more general subtitle filtering infrastructure. I pondered whether to reuse the audio/video filtering stuff - but better not. Also, since subtitles are horrible and tend to refuse proper abstraction, it's still messed into sd_ass, instead of working on the dec_sub.c level. Actually mpv used to have subtitle "filters" and even made subtitle converters part of it, but it was fairly horrible, so don't do that again. In addition, make runtime changes possible. Since this was supposed to be a quick hack, I just decided to put all subtitle filter options into a separate option group (=> simpler change notification), to manually push the change through the playloop (like it was sort of before for OSD options), and to recreate the sub filter chain completely in every change. Should be good enough. One strangeness is that due to prefetching and such, most subtitle packets (or those some time ahead) are actually done filtering when we change, so the user still needs to manually seek to actually refresh everything. And since subtitle data is usually cached in ASS_Track (for other terrible but user-friendly reasons), we also must clear the subtitle data, but of course only on seek, since otherwise all subtitles would just disappear. What a fucking mess, but such is life. We could trigger a "refresh seek" to make this more automatic, but I don't feel like it currently. This is slightly inefficient (lots of allocations and copying), but I decided that it doesn't matter. Could matter slightly for crazy ASS subtitles that render with thousands of events. Not very well tested. Still seems to work, but I didn't have many test cases.
2020-02-16 00:02:17 +00:00
propagate = true;
}
sub: make filter_sdh a "proper" filter, allow runtime changes Until now, filter_sdh was simply a function that was called by sd_ass directly (if enabled). I want to add another filter, so it's time to turn this into a somewhat more general subtitle filtering infrastructure. I pondered whether to reuse the audio/video filtering stuff - but better not. Also, since subtitles are horrible and tend to refuse proper abstraction, it's still messed into sd_ass, instead of working on the dec_sub.c level. Actually mpv used to have subtitle "filters" and even made subtitle converters part of it, but it was fairly horrible, so don't do that again. In addition, make runtime changes possible. Since this was supposed to be a quick hack, I just decided to put all subtitle filter options into a separate option group (=> simpler change notification), to manually push the change through the playloop (like it was sort of before for OSD options), and to recreate the sub filter chain completely in every change. Should be good enough. One strangeness is that due to prefetching and such, most subtitle packets (or those some time ahead) are actually done filtering when we change, so the user still needs to manually seek to actually refresh everything. And since subtitle data is usually cached in ASS_Track (for other terrible but user-friendly reasons), we also must clear the subtitle data, but of course only on seek, since otherwise all subtitles would just disappear. What a fucking mess, but such is life. We could trigger a "refresh seek" to make this more automatic, but I don't feel like it currently. This is slightly inefficient (lots of allocations and copying), but I decided that it doesn't matter. Could matter slightly for crazy ASS subtitles that render with thousands of events. Not very well tested. Still seems to work, but I didn't have many test cases.
2020-02-16 00:02:17 +00:00
if (propagate && sub->sd->driver->control)
r = sub->sd->driver->control(sub->sd, cmd, arg);
pthread_mutex_unlock(&sub->lock);
return r;
}
void sub_set_recorder_sink(struct dec_sub *sub, struct mp_recorder_sink *sink)
{
pthread_mutex_lock(&sub->lock);
sub->recorder_sink = sink;
pthread_mutex_unlock(&sub->lock);
}
Implement backwards playback See manpage additions. This is a huge hack. You can bet there are shit tons of bugs. It's literally forcing square pegs into round holes. Hopefully, the manpage wall of text makes it clear enough that the whole shit can easily crash and burn. (Although it shouldn't literally crash. That would be a bug. It possibly _could_ start a fire by entering some sort of endless loop, not a literal one, just something where it tries to do work without making progress.) (Some obvious bugs I simply ignored for this initial version, but there's a number of potential bugs I can't even imagine. Normal playback should remain completely unaffected, though.) How this works is also described in the manpage. Basically, we demux in reverse, then we decode in reverse, then we render in reverse. The decoding part is the simplest: just reorder the decoder output. This weirdly integrates with the timeline/ordered chapter code, which also has special requirements on feeding the packets to the decoder in a non-straightforward way (it doesn't conflict, although a bugmessmass breaks correct slicing of segments, so EDL/ordered chapter playback is broken in backward direction). Backward demuxing is pretty involved. In theory, it could be much easier: simply iterating the usual demuxer output backward. But this just doesn't fit into our code, so there's a cthulhu nightmare of shit. To be specific, each stream (audio, video) is reversed separately. At least this means we can do backward playback within cached content (for example, you could play backwards in a live stream; on that note, it disables prefetching, which would lead to losing new live video, but this could be avoided). The fuckmess also meant that I didn't bother trying to support subtitles. Subtitles are a problem because they're "sparse" streams. They need to be "passively" demuxed: you don't try to read a subtitle packet, you demux audio and video, and then look whether there was a subtitle packet. This means to get subtitles for a time range, you need to know that you demuxed video and audio over this range, which becomes pretty messy when you demux audio and video backwards separately. Backward display is the most weird (and potentially buggy) part. To avoid that we need to touch a LOT of timing code, we negate all timestamps. The basic idea is that due to the navigation, all comparisons and subtractions of timestamps keep working, and you don't need to touch every single of them to "reverse" them. E.g.: bool before = pts_a < pts_b; would need to be: bool before = forward ? pts_a < pts_b : pts_a > pts_b; or: bool before = pts_a * dir < pts_b * dir; or if you, as it's implemented now, just do this after decoding: pts_a *= dir; pts_b *= dir; and then in the normal timing/renderer code: bool before = pts_a < pts_b; Consequently, we don't need many changes in the latter code. But some assumptions inhererently true for forward playback may have been broken anyway. What is mainly needed is fixing places where values are passed between positive and negative "domains". For example, seeking and timestamp user display always uses positive timestamps. The main mess is that it's not obvious which domain a given variable should or does use. Well, in my tests with a single file, it suddenly started to work when I did this. I'm honestly surprised that it did, and that I didn't have to change a single line in the timing code past decoder (just something minor to make external/cached text subtitles display). I committed it immediately while avoiding thinking about it. But there really likely are subtle problems of all sorts. As far as I'm aware, gstreamer also supports backward playback. When I looked at this years ago, I couldn't find a way to actually try this, and I didn't revisit it now. Back then I also read talk slides from the person who implemented it, and I'm not sure if and which ideas I might have taken from it. It's possible that the timestamp reversal is inspired by it, but I didn't check. (I think it claimed that it could avoid large changes by changing a sign?) VapourSynth has some sort of reverse function, which provides a backward view on a video. The function itself is trivial to implement, as VapourSynth aims to provide random access to video by frame numbers (so you just request decreasing frame numbers). From what I remember, it wasn't exactly fluid, but it worked. It's implemented by creating an index, and seeking to the target on demand, and a bunch of caching. mpv could use it, but it would either require using VapourSynth as demuxer and decoder for everything, or replacing the current file every time something is supposed to be played backwards. FFmpeg's libavfilter has reversal filters for audio and video. These require buffering the entire media data of the file, and don't really fit into mpv's architecture. It could be used by playing a libavfilter graph that also demuxes, but that's like VapourSynth but worse.
2019-05-18 00:10:51 +00:00
void sub_set_play_dir(struct dec_sub *sub, int dir)
{
pthread_mutex_lock(&sub->lock);
sub->play_dir = dir;
pthread_mutex_unlock(&sub->lock);
}
bool sub_is_secondary_visible(struct dec_sub *sub)
{
return !!sub->opts->sec_sub_visibility;
}